The quality of cast metal parts is very dependent upon the design of the rigging system (sprue, runners, gates and risers). Traditionally, designing a rigging system is implemented manually given a set of drawings or model to visualize the casting dimensions and geometric features. The design procedure of mold rigging system can be made quite simple, through the use of computers. However this requires a method of describing the geometry (which plays a central rule in rigging design) of casting part in an easy and non-expensive way; the basic group technology classification is such a method, making use of a digital coding system. This paper presents the development of such a system to be mainly implemented for the mold rigging design in sand casting.